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Marin IJ Articles

Native bulbs, corms and rhizomes aren’t fussy

  • Barbara Robertson
  • November is the perfect time to plant bulbs for spring flowers. This year, though, instead of planning to tiptoe through the tulips in April, why not go native and traipse through the Triteleia, admire an Allium and then cha cha cha with a Calochortus instead? Like the non-natives, they lie dormant for half the year or so, and then burst through the ground and flower.

    If you’re a lazy gardener like me, you’ll love the beautiful native flowers and the lack of fussiness most native bulbs, corms and rhizomes require. Unlike non-natives, these plants can tolerate our wet winters and dry summers — in fact, most require them. And, if planted properly, they need little maintenance. Ever.

    Bulbs, corms and rhizomes, native or not, are all monocots, plants that produce a single leaf on the first shoot and have flower parts usually in threes or multiples of three. But unlike other monocots, this group of plants has both underground and above-ground stems. That is, the bulb, corm or rhizome that’s planted underground is actually a stem that stores food until it’s time to send a shoot into the sun; roots grow down from the bottom.

    Bulbs have a complex anatomy. If you cut apart a bulb, you’ll see an embryo of a new plant — a tiny stem and flower surrounded by fleshy modified leaves called scales, which hold the food reserves. Some bulbs, like tulips, have a skin called a tunic; others, like lilies, don’t. To propagate bulbs, pop off the miniature bulbs, the bulblets, that form at the base of the parent and plant them. The parent lives on. Native spring-flowering bulbs include the pink ornamental Alliums — meadow onions, and the white, yellow, and lavender Calochortus or Mariposa lilies. Recommended natives in these genera include Allium unifolium and Calchortus tolmiei.

    A corm is a solid stem that doesn’t have the fleshy scales. Corms are usually rounded or flat on top, and have dry scales held together at the base like a gladiolus. A corm reproduces by forming new corms on top of old, withered corms and miniature corms, the cormels or cormlets, between the old and new corms. The parent dies out. A recommended native is the blue Triteleia laxa, also known as Ithuriel’s spear.

    Rhizomes are thick stems that grow horizontally underground, like bamboo. To propagate a rhizome, cut it into sections with each having a bud or eye, and then plant that section. A popular native flowering rhizome is Iris douglasiana, the Douglas iris, one of the few natives that can tolerate slightly richer soil and a little summer water.

    Most native bulbs, corms and rhizomes will rot with summer water. They need full or part sun and a spot far from sprinklers and other sources of water in the garden. Plant them after the first rain in late fall, root end of the bulb or corm pointing down, three to six inches deep. Plant rhizomes root down, eyes up, with the top of the rhizome visible at the soil surface. Do not amend the soil. Once planted, clear the area of weeds. And, guard against native pests like snails, slugs and gophers.

    If you can’t keep the natives summer dry, consider putting them in pots and give them a little fresh potting soil or mild fertilizer each fall.

    You can search for Marin and California natives on the California Native Plant Society website (cnps.org), and in the Calflora Database (calflora.org). The California Native Plant Link Exchange (cnplx.info) can also help you select native plants for your particular location, learn about the plants and discover where to buy them. Be sure to buy from reputable dealers who propagate their bulbs rather than collect them from the wild.

    And then relax knowing these bulbs, corms and rhizomes will tiptoe through our wet winters and dry summers without your help.